Firing mechanism for automatic firearms



May 5, 1931. G. H. TANSLEY FIRING MECHANISM FOR AUTOMATIC FIREARMS Filed Dec.

, fiyr nbar v mm UN m iaazyaHTms/gz Frag Patented May 5, 1931 UNITED STATES PATENT OFFICE? GEORGE H. TAN SLEY, F HARTFORD, CONNECTICUT, ASSIGNOR COLTS PATENT FIRE ARMS MANUFACTURING 00., OF HARTFQRD, CONNECTICUT, A CORPORATION OF comorrour.

FIRING MECHANISM FOR AUTOMATIC FIREARMS Application filed December 12, 1929. Serial No. 413,610.

The present invention is particularly applicable to a machine gun constructed as shown and described in Patent No. 1,293,021 issued February'4, 1919, to J o'hn M. Browning, but

it will be understood that the invention is not necessarily so limited.

An automatic machine gun of this general class is frequently required to be mounted in a relatively fixed position on an airplane and 1 fired in synchronism with the rotation of the propeller so as to fire between the propeller blades without hitting them. Various synchronizing'mechanisms and trigger motors have been devised for controlling the firing of guns mounted as described and a gun embodying the present invention is adapted to be used with a synchronizing mechanism and trigger motor of known design.

In the mounting of a gun on an airplane, it is sometimes preferable to have the trigger motor engage the gun at the right side thereof and it is sometimes preferable to have it engage the gun at the left side thereof. The principal object of the present invention is to provide a gun so constructed that the trigger motor can be applied thereto at'either side. The construction of the firing mechanism of the gun is such thatxby merely reversing the positions of certain parts the gun can be adapted for operation'by means of a trigger motor at either side.

Further objects of the invention will be apparent from the following specification and claims; v

In the accompanying drawing I have shown a machine gun similar in many respects to that shown in the before "mentioned Browning patent and reference can be had to that patent for such details of construction 40 as may not be fully apparent from the present drawing and description. As concerns the parts of the gun to which the invention particularly relates, it is to be understood that the drawing is for illustrative purposes only and is not to be construed as defining or limiting the scope of the invention, the claims forming a part of this invention being relied upon for that purpose.

Of the drawing:

Fig. 1 is a vertical longitudinal sectional view of a firearm embodying the invention.

Fig. 2 is a fragmentary view similar to Fig. 1 but showing the parts in different relative positions.

Fig. 3 is a fragmentary longitudinal sec tional view similar to Fig. 1 but showing a manual firing mechanism substituted at the rear.-

Fig. 4 is a fragmentary rear view of the breech bolt and immediately associated parts, this view showing a portion of the breech casing in section.

Fig. 5 is a fragmentary vertical longitudinal sectional view taken along the line 5--5 of Fig. 4.

Fig. 6 is a fragmentary horizontal sectional view taken along the line 6-6 of Fig. 4.

Fig. 7 is a view similar to Fig. 4 but show-. ing some ofthe parts in different positions.

Fig. 8.is a view similar to Fig. 6 but showing the parts in the same poistions as in Fig. 7.

Figs. 9, 10 and 11 are top, rear and side views respectively of the sear.

Figs. 12, 13 and '14 are top, rear and side views respectively of the sear operating member.

- Fig. 15 is a perspective view of the pin lever for holding the operating member in place.

The machine gun as shown in the drawing comprises a breech casing 1 which contains. the breech mechanism, this casing being rectangular in form and having two side plates 2, 2 connected at t-he front with a trunnion block 3. The rear part of the bottom of the casing is closed by a transverse bottom plate 4 and the rear part of the top of the casing is closed by thetop plate 5. In front of the plate 5 there is also provided a cover 6 pivoted at 7 so that it can be swung upward to expose theinterior parts. The cover 6 is normally held closed by means of a latch at 8.

The casing is closed at the rear by means of a plate 9 which is vertically movable in oves (not shown) formed in the two side plates 2, 2. The plate 9 is held in place by a manually releasable pivoted latch 9. The

plate 9 carries a buffer mechanism indicated as an entirety by 10.

In Fig. 3.1 have shown an alternate rear plate 9 which may be substituted for the plate 9 already described. The plate 9 carries a buffer mechanism 10 and in addition carries a manually operable trigger 11 having a lower rear portion projecting forward through a hole in the plate. The plate 9' is intended to be substituted for the plate 9 when it is desired to fire the gun manually either for testing purposes or for regular service as a. ground gun.

'Projecting from the casing at the front is a barrel 12 which upon arecoil is movable rearward to a limited extent. The barrel extends through a bearing aperture 13 in the trunnion block 3 and it has another bearing at or near the forward end of the barrel jacket 14, the said jacket being carried by a flange 15 formed on the trunnion block. Connectedwith the barrel 12 at the rear end thereof andbodily movable therewith is a is a breech bolt 17. This breech bolt is provided at its opposite sides withlongitudinal tongues 17, 17 adapted to enter longitudinal grooves 16 formed in the side members 16 of the barrel extension. The rear part of the breech bolt 17 is extended transversely, as clearly shown in Figs. 4 and 6 so as to occupy the entire width of the casing between the two side plates 2, 2. A reaction spring 18 is provided which extends into a longitudinal opening 19 in the breech bolt and which tends to hold the breech bolt in its forward position. Upon recoil this reaction spring is compressed' and immediately tends to return the breech bolt in the forward direction.

Mounted in the rear lower part of the casing is a lock frame 20 comprising-two side members lying closely adjacent the side Walls 2, 2 of the casing. Immediately in front of the lock frame 20 is a transverse block 21 secured to the bottom wall 4. When the parts are in their forward positions as shown in Fig. 1 the breech bolt is locked to the barrel extension by means of a lock bolt 22 vertically movable in a recess in the transverse portion 16 of the barrel extension and entering a notch 23 in the breech bolt. The lock bolt 22 is held in its upper locking position by means of the transverse block 21, but when the barrel extension and breech bolt move rearward, the said lock bolt is moved downward by means, of cam surfaces 24 formed at the forward=endsfof the lock frame 20.

This permits the breech bolt to move rearward independently of the barrel extension as clearly shown in Fig. 2. When the parts are returned to. their forward positions the lock bolt 22is again moved to locking position by means of the cam surface 25 on the block'21.

Transversely pivoted on the lock frame 20 is a rock lever or accelerator 26 having a convex forward facing surface adapted to be engaged by the rear surface of the barrel extension. When the barrel extension moves rearward upon recoil the breech bolt is unlocked therefrom in the manner already described and the accelerator 26 is moved in the counter-clockwise direction. The upper end of the accelerator engages the surface 27 on the breech bolt and the accelerator thus serves to assist or accelerate the rearward movement of the bolt, acting as a means for transmitting the energy of the relatively heavy barrel extension and barrel to the lighter breech bolt. As the breech bolt moves rearward the surface 27 is separated from the accelerator and the bottom of the breech bolt movesover the accelerator thus holding it in its rear-most position as clearly shown in Fig. 2. When the accelerator is in this position an extension 26 thereof engages an extension 16 on the barrel extension to positively hold the said barrel extension in its rearmost position until suchtime as the breech bolt moves forward.

Carried by the lock frame 20 is a slidable rod 28 surrounded by a coil spring 29 tending to move the rod toward the front. The extension 16 on the barrel extension abuts against the front end of the rod and the spring 29 thus serves to resist rearward movement of the barrel extension and to assist forward movement thereof.

The breech bolt 17 has a central longitudinal opening therein adapted to receive the firing pin 30. The firing pin 30 is hollow having a spring 31 therein which abuts at its rear against a vertical pin extending through a slot 30 in the firing pin. The spring 31 thus serves to bias the firing pin for movementin the forward direction. Pivotally mounted on the breech bolt is a cocking lever 32 mounted on a removable transverse pin 32. The upper end of the cooking lever extends into a suitable slot in a block 33 secured to the top wall 5 of the casing, and the lower end extends into the slot 30 in the firing pin. The cooking lever is so formed and positioned that, when the breech bolt moves rearward, the cocking lever is turned in the clockwise direction andserves to move the firing pin relatively rearward to its cocked position where it is engaged by the sear to be presently described.

Pivotally mounted on the breech bolt at the left side thereof is an extractor 34 controlled by a cam spring 35 and a cam rib 35 on the cover 6 and further controlled by cam plates from the feed mechanism at the front and is moved downward by reason of engagement with the cams and 35. As the breech bolt moves forward the cartridge is moved into the firing chamber of the barrel and the extractor is returned bythe cam 36 to its up- I per position as shown in Fig. 1 where it engages the next cartridge.- When the feed mechanism is reversible as is preferred and as is hereinafter described, certain portions of the extractor are also reversible but this constitutes no part of the present invention.

' The movements of; the barrel extension and breech bolt and other parts as described ordinarily occur automatically as the result of the recoil action of the firearm. However, in orderto test the mechanism and in order to place the first cartridge in the firing chamber, means is provided for operating the parts manually. One of the side walls 2 of I the casing is provided with a longitudinal slot 37 and preferably there is such a slot in each side wall. A pin 38 is provided which may be inserted through either slot into a suitable transverse hole in the breech bolt. The pin 38 is held in place by a shoulder (not shown) which engages the corresponding side plate at'the edges of the slot 37. The slots 37 are enlarged at the rear to permit the removal or insertion of the pin.

As shown most clearly in Figs. 4, 5 and 6 the breech bolt 17 is provided at the rear with a transverse horizontal slot or guideway in which is located a transversely and horizontally movable sear 40. The sear has a forward extending hook portion 40 which is adapted to engage a locking shoulder 30 formed on the firing pin 30 near the rear thereof. Preferably the shoulder 30 is the rear wall of a notch cut into the pin.

Carried by the breech bolt immediately adacent the sear 40 is a vertically movable sear operating member 41. The member 41 is guided for rectilinear movement in a vertical slot 42 in the breech bolt and it is operatively connected with the sear so that'when the said member is moved vertically the sear is moved horizontally. 4

Projecting from the top of the operating member 41 is a spring plunger 43 which normally abuts against the rear endportion of a pin lever 44 shown in detail in Fig. 15. As shown in Fig. 1 the forward pivot pin of this lever is adapted to be located in a vertical hole in the bottom of a longitudinal slot 17 b at the top of the breech bolt. This pin forming a part of the lever preferably serves as the aforesaid pin against which the spring 31 abuts at the rear. The. lever 44 is recessed at 44 to clear the cocking lever 32. The rear part of the lever 44 is normally positioned in a notch at the left side of the slot 17 as shown in Fig. 4. When the cocking lever has been I removed the lever 44 may be swung toward the right and removed thus permitting removal of the operating member 41. It will be apparent that the spring plunger 43 reacting against the lever 44 tends to move the operating member 41 downward and to holdit in its lowermost position as shown in Fig. 4.

Carried by the sear at the rear side thereof is a transversely movable spring plunger 45. When the operating member 41 is in place as shown in Fig. 4 the inner end of the spring plunger 45' abuts against the said member thus biasing the sear for movement in the direction to engage and hold the firing pin, in this case toward the left as clearly shown in Fig. 6.

Preferably the member 41 has a lug 41 at the rear which abuts against the top of the scar and limits downward movement. The lug 41" preferably has a V-point as shown which enters a similarly shaped notch 40 in the sear. The lug 41 thus serves as a detent to releasably hold the sear in its operative position, supplementing the action of the spring plunger 45.

The operative connection between the operating member 41 and the sear 40 is preferably provided by means of interengaging cam surfaces. As shown and as preferred the the sear is'provided at the rear with a laterally facing cam surface at 40. As a matter of convenience of construction this cam surface 40 may be the peripheral surface of a cylindrical boss projecting rearward from the sear. The operating member 41 is provided at the right with a recess 41 the wall of member and the sear is held in its extreme.-

,leasing the firing pin. When the member 41 is moved downward by the spring plunger 43, the seatis returned to normal position by the spring plunger 45in cooperation with the detent 41*.

For manual firing the substitute rearplate 9 is used, as already stated. The sear operating member 41may be moved vertically upward by means of a trigger lever 46 pivoted to the lock frame 20. This lever is so' 1 located that it may be engaged at the rear by the trigger 11 carried by the plate 9. The front end of the lever 46 is below and in operative relation to the member 41 when the breech bolt and associated parts are in airplane.

their forward firing positions as shown in Fig. 1. When the trigger 11 is pressed the member 41 is moved upward in opposition to the plunger 42, thus moving the sear 40 horizontally. and releasing the firing pin'30.

A ,firearm embodying the present invention, while capable of being fired manually as described, is primarily intended to be fired automatically by means of a trigger motor such as M actuated by a suitable synchronizing mechanism as already stated. Provision is preferably made for mounting the trigger motor at either the left or the right side of the casing 1. Fig. 4 shows the trigger motor at the left and Fig. 7 shows it at the right. At the side of the casing opposite the trigger motor is a bracket 39 for a part of the manual operating mechanism of the firearm. I

When provision is made for mounting the trigger motor at either side, the sear 40 is so constructed as to be reversible. It may occupy either-the position shown in Figs. 4 to 6 or the position shown in Figs. 7 and 8. In this latter position the hook portion 40 of the sear no longer engages the shoulder of the firing pm but engages a. similar shoulder 30 at the left side thereof.

The operating member 41 is provided at the left with a recess 41 similar to the recess 41" and adapted to similarly cooperate with the cam surface on the sear when the sear is in the reversed position. It will be understood that in order to reverse the position of the sear it is necessary to first remove the operating member 41. However, when the sear has been reversed the member 41 is replaced-in exactly the same position. as before, the cam portion 40 of the sear entering the recess at the left instead of the recess at the right, and the lug 11:1 of the operating member enters a second sear notch 40 similar to and opposite the first mentioned notch 40". The spring plunger 45 on the sear abuts against the member 41 as before except that it engages the right hand side instead of the left hand side.

The trigger motor M need not be fully described, but as shown the said motor comprises a transversely moving actuating memher 122. which is adapted to operate the firing mechanism when the breech bolt is in its forward firing position. The member m serves to directly engage the sear and move the sear r in the direction necessary to release the firing pin. Impulses are transmitted to the member m by means of a longitudinally movable plunger m actuated by a lever m. cable or lanyard may be connected to the lever m to transmit motion from a suitable mechanism timed with the propeller of the Thus the member m'is operated in timed relation with the propeller. When the trigger motor is at the left, as shown in Fig. 4, the lanyard is connected at the bottom, and when the trigger motor is at the right, as shown in Fig. 7, the lanyard is connected at the top.

Inoperation the trigger motor is actuated as already described in synchronism with the rotation of the propeller, with the result that the member m is rapidly reciprocated transversely. When the gun has once been fired the parts move rearward during recoil in the manner already described and then return tothe-forward firing position. After the parts reach the said forward firing position, firing takes place upon the next inward movement of the actuating member m. Ordinarily thereciprocation of the member m is much more rapid than the firing action of the gun, with the result that firing occurs immediately, or substantially immediately, upon the return of the breech bolt to its forward firing position.

IVhat I claim is:

1. In an automatic firearm, the combination of a breech boltlongitudinally reciprocable upon recoil, a spring actuated firing pin movable longitudinally of the breech bolt, a cocking lever on the breech bolt acting automatically during recoil to move the firing pin relatively rearward to cocked position, a transversely and horizontally movable sear carried by the breech bolt and biased for movement in one direction to engage the firing pin to hold it in cocked position, and a member carried by the breech bolt adjacent the sear and guided for vertical rectilinear movement, the said member being operatively connected with the sear so that when the member is moved vertically the sear is moved horizontally in the direction opposite to the first said direction to release the firing pin.

2. In an automatic firearm, the combination of a breech bolt longitudinally reciprocable upon recoil, a spring actuated firing pin movable longitudinally of the breech bolt, a cocking lever on the. breech bolt acting automatically during recoil to move the firing pin relatively rearward to cocked position, a transversely and horizontally movable sear having a laterally facing cam surface thereon, the said sear being carried by the breech bolt and being biased for movement in one direction to engage the firing pin to hold it in cocked position, and a member carried by the breech bolt adjacent the sear and guided for vertical rectilinear movement, the said member having a cam surface adapted to engage the cam surface on the said sear and serving when the member is moved vertically to move the sear horizontally in the direction opposite to the first said direction to release the firing pin.

3. In an automatic firearm, the combination of a breech bolt longitudinally reciprocable upon recoil, a spring actuated firing pin movable longitudinally of the breech bolt, a cocking lever on the breech bolt acting autowith the sear so that when the member is moved vertically the scan is moved horizontally in the direction opposite to the first said direction to release the firing pin.

4. In an'automatic firearm, the combination of a' breech bolt longitudinally reciprocable upon recoil, a spring actuated firing .pin

movable longitudinally of the breech bolt, a

cocking lever on thebreech bolt acting automovement in one matically during recoil to move the firing pin relatively rearward to cocked position, a transversely and horizontally movable sear carried by the breech bolt and biased for direction to engage the firing pin to hold it in cocked position, a member carried by the breech bolt adjacent the scar and guided for vertical rectilinear movement, thesaid member being operatively connected with the sear so that when the member is moved vertically the scar is moved horizontally in the direction 0 posite to the first said direction to release't e firing pin,

and a lug on thelast said-member normally engaging the soar to releasably hold it in its normal pin engaging position,

' 5. Inan automatic firearm, the combination of a breech bolt longitudinally reciprocable upon recoil,-a spring actuated firing pin movable longitudinally of the breech bolt, a

cocking lever on the breech bolt acting automatically during recoil to move the firing pin I relatively rearwardto cocked position, a transversely and horizontally movable sear carried by the breech boltand reversible in position with respect thereto, means for biasing thev sear for movement in one-direction or the other accordin to its positionvso as to engage the firing pin to holdit in cocked position, and a member carried by the breech bolt adjacent the scar and guided for-vertical rectilinear movement, the said member being operatively connected with the sear with the latter in either of its relatively reversed positions so that when the member is moved vertically the sear is moved horizontallyin the direction opposite to its bias to release the firing pin.

6. In an automatic firearm, the combination of a breech bolt longitudinally reciprocable upon recoil, a spring actuated firing pin movable longitudinally of the breech bolt, a

cocking lever on the breech bolt acting automatically during recoil to move the firing pin relatively rearward to cocked position, a

transversely and horizontally movable sear having a laterally facing cam surface thereon, the said sear being carried by the breech bolt and being reversible in position with respect thereto, means for biasing the sear for movement in one direction or the other according to its position so as to engage the firing pin to hold it in cocked position, and a member carried by the breech bolt adjacent the sear and guided for vertical rectilinear movement,

the said member having oppositely disposed cam surfaces either of which may engage the cam surface on the sear according to the position thereof so .as to serve upon vertical movement of the member to move the sear horizontally in the direction opposite to its bias to release the firing pin. w

7. In an automatic firearm, the combination of-a breech bolt longitudinally recipro- I cable upon recoll, a spring actuated firing pin movable longitudinally of the breech bolt, a cocking leveron the breech bolt acting automatically during recoil to move the firing pin relatively rearward to cocked position, a

transversely and horizontally movable sear carried by the breech bolt and reversible in position with respect thereto, a spring pressed plunger carried by the sear for biasing it in one direction or the other according to its position so as to engage the firing pinto hold it in cocked position, and an abutment means with which the plunger engages in each position of the sear.

8. In an automatic firearm, the combination of a breech bolt longitudinally reciprocable upon recoil, a spring actuated firing pin movable longitudinally of the breech bolt,

acocking lever on the breech bolt acting automatically during recoil to move the firing pin relatively rearward to cocked position, a transversely and horizontally movable sear carried by the breech bolt. and reversible in position with respect thereto, a spring pressed plunger carried by the sear for biasing it in one directionor the'other according to its- 0- sition so as to engage the firing pin to hol it in cocked position, a vertically movable member carried by thebreech bolt adjacent the scar and serving as an abutment means with which the plunger engages in each position of the sear, the said member being operatively connected with the sear with the latter in either of its relatively reversed positions so that when the member is moved vertically the sear is moved horizontally in the direction opposite to its bias to release the firing pin.

In testimony whereof I have hereunto set my hand this 9th day of December, 1929.

, GEORGE H. TANSLEY. 

